A microwave oven is a cooking device that cooks food by passing a microwave through the food. The microwave oven uses a magnetron to generate the microwave from an electric current.
Generally, a microwave oven is a device that is used to heat food by radiating microwave generated from a magnetron to the food when electric current is applied to electric components of the device.
Such a microwave oven is classified into a household microwave oven having a small magnetron and a commercial microwave oven having a large (or a plurality of) magnetron. The microwave oven is further classified according to a heating method into a glass tray method rotating the food and a stirrer fan method scattering microwave radiated into the cavity. The former is generally applied to the household microwave oven while the latter is applied to the commercial microwave oven. In the stirrer fan method, a stirrer is used to uniformly distribute the microwave about a cavity where food is loaded. Since the commercial microwave oven is generally used at convenience stores where the microwave oven is frequently used and restaurants where a large amount of the food should be quickly heated, the commercial microwave oven needs relatively high power output compared with the household microwave oven.
A microwave oven of the stirrer fan method includes: a magnetron for generating microwave; a waveguide provided at an upper side and lower side of a cavity, for guiding the generated microwave from the magnetron toward a cavity, in which food is loaded; a stirrer fan disposed at an outlet of the waveguide; and a motor for driving the stirrer fan. To fix the motor on an outside surface of the waveguide, a screw is used and the screw is protruded from an inside surface of the waveguide. A screw covering part is provided at the inside surface of the waveguide, where the screw is protruded, in order to prevent the protruded screw from interrupting the microwave flow.
In operation, the microwave generated at the magnetron passes from an inlet of the waveguide and to an outlet of the waveguide, and enters the cavity while scattered and reflected by the stirrer fan. The microwave can be uniformly distributed about the cavity owing to the stirrer fan and thereby food can be cooked evenly.
However, the related art structure for radiating microwave has several drawbacks.
The screw covering part narrows the microwave passage in the waveguide and thereby the microwave is converged with an undesired pattern, this causes the microwave to be unevenly distributed about the cavity, such that the cavity can be partially stained with soot due to partial exposure to intensive microwave and of cause food cannot be evenly cooked.
Further, though the stirrer fan scatters and reflects the microwave into the cavity, the microwave is not sufficiently distributed about the cavity so that food cannot be cooked evenly.
Furthermore, because of the non-uniform distribution of the microwave in the cavity, it takes much more time to cook the food.